def f(x):
    return x * x

#一进一出
r = map(f, [1, 2, 3, 4, 5, 6, 7, 8, 9])
print(list(r))

L = []
for n in [1, 2, 3, 4, 5, 6, 7, 8, 9]:
    L.append(f(n))
print(L)

print(list(map(str, [1, 2, 3, 4, 5, 6, 7, 8, 9])))

from functools import reduce

#多进一出
def add(x, y):
    return x + y
print(reduce(add, [1, 3, 5, 7, 9]))